SB4000 Support Thread

[ruckus328]

I re-seated the U11 (right VCA) and presto! I have audio on both channels again..
I redid step 2, and whent on to step 3 of the calibration, but still nothing on TP11.. Any way to measure K6 from the top? Otherwise i will have to dismount all wires to be able to turn it around.. In that case: what do I need to connect to be able to test K6 relay? Just PSU or do i need to connect everything with the main PCB upside down?

Mica, look on the schematic.  Follow the signal with your multimeter.  Start at the input and work your way to TP11.  Whenever the signal stops, you've found your problem.


Harpo - thanks for the help!

 

[mica]

I re-seated the U11 (right VCA) and presto! I have audio on both channels again..
I redid step 2, and whent on to step 3 of the calibration, but still nothing on TP11.. Any way to measure K6 from the top? Otherwise i will have to dismount all wires to be able to turn it around.. In that case: what do I need to connect to be able to test K6 relay? Just PSU or do i need to connect everything with the main PCB upside down?

Mica, look on the schematic.  Follow the signal with your multimeter.  Start at the input and work your way to TP11.  Whenever the signal stops, you've found your problem.


Harpo - thanks for the help!

Im **** at schematics, but im having some help on how and where to measure for problems from the danish board.... This is my 6th DIY build, and i rarely make mistakes (hence i never have to look at schmatics) but when i DO make an error, im really lost im affraid.. Thank you for all your help though. Im learning more and more for each build..

 

[mica]

Well.. the unit is paasing audio on both channels, and it sunds like its compressing.. Its responding to makeupgain on both chanels as well.
No voltage on TP 11+ TP12 with testone on INPUT L+R..

Ive done some measurements:

12K ohm / 0 ohm between pin17 on J6 and R56

IC readings (between pin 4 &  8) DC:

U7: 30.43v
U2: 30.44v
U6: 30.43v
U1: 30.44v
U3: 27.77v
U5: 27.87v
U8: 30.44v
U4: 30.44v
U13: 24.00v
U12: 27.73v
U18: 27.80v

EXT IN switch up:

Test tone in Ext. Send:

1.5V on TP11 (and 0v on TP12)..

Test tone in Ext. Return:

1.13V on TP12 (and 0v on TP11)

EXT IN switch down:

0v on both TP12 and TP11

 

[Harpo]

Well.. the unit is paasing audio on both channels, and it sunds like its compressing.. Its responding to makeupgain on both chanels as well.
No voltage on TP 11+ TP12 with testone on INPUT L+R..

Ive done some measurements:

do some more measurements ... there will be no compression without signal at TP11 and TP12.

1) Feed only left side input with audio signal and measure AC voltage with respect to 0V reference voltage at 'TP8'. Write down this measured amount.
2) Confirm, switching the unit to bypass would set this value to 0V, so reading 0V with signal present you'd know you are in bypass mode or relais K4 isn't operating as should.
3) Set internal sidechain mode switch to Stereo/Oxford/Turbo mode. Measuring AC voltage at 'TP9' should give the same readout as 'TP8' and 0V when activating Mono/GSSL mode, so reading 0V with signal present you'd know you are in Mono mode or relais K5 isn't operating as should.
4) Same voltage readout will be measured at External-Send-L at J3-pin1 (further going to 'R' from a TRS-socket or XLR-pin3 that an XLR_to_2x_TS-plug Y-adapter cable might connect to, so you could feed an external device, maybe an EQ, with this unbalanced output from this buffered signal voltage with your left side signal input) and J6-pin11.
5) With HPF set to 'off', same voltage should show up on J6-pin13.
6) With external-input switch set to disabled, same voltage should show up at 'TP11'.
7) With external-input switch set to enabled and operated signal from step 4 comming back from your unbalanced external waveshaping device thru 'T' from a TRS-socket with 'S' connected to ground or XLR-pin2 with XLR-pin1 connected to ground that an XLR_to_2x_TS-plug Y-adapter cable might connect to, further connecting to J3-pin2, shaped/external signal voltage should show up at 'TP11', but voltage readout might be different from external waveshaping. (testing for same signal voltage as in previous steps, you could use a plug with T/R shorted or a XLR-plug with pins 2/3 shorted or the connected external device might be switched to bypass)
right side audio) Disconnect left side signal input and connect same cable to right side signal input, so voltage readout should be the same when going thru steps 1...7, but at the corresponding right side connectors/nodes/testpoints and the other TRS or XLR socket for external send/return.
Good luck

 

[sr1200]

Dumb question alert: are you measuring AC or DC with your meter?

 

[mica]

Dumb question alert: are you measuring AC or DC with your meter?

Only DC to measure powerrails (calibration step 1) and ICs.. rest is AC measures

 

[mica]

Well.. the unit is paasing audio on both channels, and it sunds like its compressing.. Its responding to makeupgain on both chanels as well.
No voltage on TP 11+ TP12 with testone on INPUT L+R..

Ive done some measurements:

do some more measurements ... there will be no compression without signal at TP11 and TP12.

1) Feed only left side input with audio signal and measure AC voltage with respect to 0V reference voltage at 'TP8'. Write down this measured amount.
2) Confirm, switching the unit to bypass would set this value to 0V, so reading 0V with signal present you'd know you are in bypass mode or relais K4 isn't operating as should.
3) Set internal sidechain mode switch to Stereo/Oxford/Turbo mode. Measuring AC voltage at 'TP9' should give the same readout as 'TP8' and 0V when activating Mono/GSSL mode, so reading 0V with signal present you'd know you are in Mono mode or relais K5 isn't operating as should.
4) Same voltage readout will be measured at External-Send-L at J3-pin1 (further going to 'R' from a TRS-socket or XLR-pin3 that an XLR_to_2x_TS-plug Y-adapter cable might connect to, so you could feed an external device, maybe an EQ, with this unbalanced output from this buffered signal voltage with your left side signal input) and J6-pin11.
5) With HPF set to 'off', same voltage should show up on J6-pin13.
6) With external-input switch set to disabled, same voltage should show up at 'TP11'.
7) With external-input switch set to enabled and operated signal from step 4 comming back from your unbalanced external waveshaping device thru 'T' from a TRS-socket with 'S' connected to ground or XLR-pin2 with XLR-pin1 connected to ground that an XLR_to_2x_TS-plug Y-adapter cable might connect to, further connecting to J3-pin2, shaped/external signal voltage should show up at 'TP11', but voltage readout might be different from external waveshaping. (testing for same signal voltage as in previous steps, you could use a plug with T/R shorted or a XLR-plug with pins 2/3 shorted or the connected external device might be switched to bypass)
right side audio) Disconnect left side signal input and connect same cable to right side signal input, so voltage readout should be the same when going thru steps 1...7, but at the corresponding right side connectors/nodes/testpoints and the other TRS or XLR socket for external send/return.
Good luck

Step 1-4 ok. reading 3.5V on TP8+9 and 0v when bypassed or in mono as described.. J3 pin1 also 3.5V and 0v bypassed..

got to step 5..
I cant really measure anything on J6 with the ribboncable attached.. I have tried to measure pin13 on J18 (from the front of the controll pcb) and that reads 6v with HPF set in the OFF position.. (and with the ribboncable attached to both main and controller pcb)
If i remove the ribbon from the main pcb and measure pin13 on J6 i also get 6V AC.. (3v in mono and 0v when bypassed)

make any sense?

/M

 

[Harpo]

Step 1-4 ok. reading 3.5V on TP8+9 and 0v when bypassed or in mono as described.. J3 pin1 also 3.5V and 0v bypassed..

got to step 5..
I cant really measure anything on J6 with the ribboncable attached.. I have tried to measure pin13 on J18 (from the front of the controll pcb) and that reads 6v with HPF set in the OFF position.. (and with the ribboncable attached to both main and controller pcb)
If i remove the ribbon from the main pcb and measure pin13 on J6 i also get 6V AC.. (3v in mono and 0v when bypassed)

make any sense?

/M

'i also get 6V AC.. (3v in mono and 0v when bypassed)' doesn't make sense. Shouldn't read 6VAC but same 3.5VAC with ribbon connected and 0V with 'external in' disabled. Double check your meters battery isn't low.
Reading other value than 0V at J6-pin13 with ribbon removed from main pcb (open end further going to K6-pin10) assumes U2b being broken, U2b-pin5 not connecting to reference voltage (IC-pin bent inwards not connecting to socket) or running open loop because of broken or poorly soldered VR8 and/or R59. As followup C89 might be broken as well. Just an idea...

 

[Dazazone]

Hello!  I have used THAT 2181A's in the quad vca board instead of 2181B's!  Is that ok or will some of the resistors on the quad vca board have to change?  Also just to confirm, the table of values on the schematic - for quad vca do you use the 202 gold can table??
Thanks dudes 

 

[Dazazone]

I'm Thinking r76 and r96 may have to be different as well? I've just put in the 15k as per the quad vca bom changes.  What about r38 and r49 too? eek!

 

[Dazazone]

Ok I'm thinking the R-76 and R-96 need to change to 170k for quad vca's with that 2181a's.  Is that right?

 

[Dazazone]

I changed the R-76 and R-96 to 180k cos that's the closest to 170k I had.  It continues onto the 50k trimmer anyway so that is good now.  All calibration worked out and It's pumpin!  Woooo!  I find this a bit better than my GSSL with mods.  Nice  8)

 

[ruckus328]

I changed the R-76 and R-96 to 180k cos that's the closest to 170k I had.  It continues onto the 50k trimmer anyway so that is good now.  All calibration worked out and It's pumpin!  Woooo!  I find this a bit better than my GSSL with mods.  Nice  8)

Symmetry resistor for 4X THAT2181 should be 1/4 of recommended resistor value on datasheet.  In this case of THAT2181A, 680K / 4= 170K, anything 160K to 180K will be fine.

 

[solderboy]

hello!
got the pcb from a friend and have one question... documentation is for trimmed vca´s. can someone please explain (like for dummies... ) what i have to do when i want to use pretrimmed vca´s on the pcb and also for the quad?

 

[MadHans]

Hi,

I have just finished the build of my unit, and everything looks good  .
I've checked the voltage at the rails(without main pcb and control board connected), and they checked out good.

Now it is time to connect the main pcb (quad vca version), and I have a couple of questions:

1) Do I check only one voltage at a time? Like this: pwr on > check +15v rail quickly > pwr off  > pwr on > check -15v rail quickly > pwr off ... etc etc. And how quick do I have to be??

2) Is it a good idea to leave the IC's and VCA's out while doing this test, and put them in after the voltage tests on the rails have checked out good? Or does it affect the voltage reading on the rails too much?
3) If it is possible to install them after the voltage test, should they be installed one by one?

4) I have read about the "47k or jump" issue on this thread, and I still don't understand what the resistor does. Many people say "jump"  but why? What is the difference?

I appreciate any help!

regards,

Hans Jacob

 

[sr1200]

Best I can tell, its like an appendix. lol

 

[solderboy]

ok, found the sheet on the schematic... now it´s more clear what´s to do for 2180´s. but i still dont get about the quad pcb. what is the 50k trimmer doing? do i have to install this trimmer for 2180´s??? would be happy about any help... 

 

[solderboy]

and another problem i got today...  :'(
i was trying out a different switch like the one from the bom. i still had this one:
http://www.conrad.de/ce/de/product/706170/SIGNALLAMPE-TYP-1-MAX-65-MM/?ref=detview
the switch is using a kind of mini-bulp 12v, 40 mA and it seem´s this is to much... or something is wrong in general with my power. when i connect a normal 12v led it´s working fine - mini-bulp: nothing. for controlling i did a connection from the 12v out of the psu to the switch: lamp is working. so... what´s wrong? is the 40mA to much? what kind of light is the switch from the bom using?

i would be extremly happy about any help...

 

[solderboy]

nobody???

 

[Harpo]

and another problem i got today...  :'(
i was trying out a different switch like the one from the bom. i still had this one:
http://www.conrad.de/ce/de/product/706170/SIGNALLAMPE-TYP-1-MAX-65-MM/?ref=detview
the switch is using a kind of mini-bulp 12v, 40 mA and it seem´s this is to much... or something is wrong in general with my power. when i connect a normal 12v led it´s working fine - mini-bulp: nothing. for controlling i did a connection from the 12v out of the psu to the switch: lamp is working. so... what´s wrong? is the 40mA to much? what kind of light is the switch from the bom using?

i would be extremly happy about any help...

You already looked at the schematic and wondered what R141 was used for ?
This 1K resistor is in series with the LED to limit the LEDs current to (12V-2V)/1000R=0.01A=10mA. You now have substituted the LED with your incandescent bulb, drawing 40mA at 12V. This bulb is equivalent to a 12V/0.04A=300R shining resistor. With R141 still in circuit, this series resistor forms a voltage divider, so there is only 12V/(1000R+300R)*300R=2.7V availiable for your bulb - obviously not enough to show up when 12V are required for the bulbs max.brightness. Using this 12V/40mA bulb, you want to decrease this R141, depending on wanted bulbs brightness or short it out for max.brightness.